"SZŰCS Gábor" <surrano@mailbox.hu> writes:
> SELECT count(*)<0 OR TRUE FROM mytable WHERE condition
> dumps the whole tuples meeting the condition.
Sigh, I'm an idiot. I introduced this bug more than a year ago.
(Bit surprising that it wasn't caught already...) Patch against 7.4.*
is attached.
regards, tom lane
Index: planner.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/optimizer/plan/planner.c,v
retrieving revision 1.161
diff -c -r1.161 planner.c
*** planner.c 25 Sep 2003 06:58:00 -0000 1.161
--- planner.c 13 Feb 2004 22:22:26 -0000
***************
*** 701,719 **** /* * Will need actual number of aggregates for estimating costs.
- * Also, it's possible that optimization has eliminated all
- * aggregates, and we may as well check for that here. * * Note: we do not attempt to
detectduplicate aggregates here; a * somewhat-overestimated count is okay for our present purposes.
*/ if (parse->hasAggs)
- { numAggs = count_agg_clause((Node *) tlist) +
count_agg_clause(parse->havingQual);
- if (numAggs == 0)
- parse->hasAggs = false;
- } /* * Figure out whether we need a sorted result from query_planner.
--- 701,718 ---- /* * Will need actual number of aggregates for estimating costs. *
*Note: we do not attempt to detect duplicate aggregates here; a * somewhat-overestimated count is okay for our
presentpurposes.
+ *
+ * Note: think not that we can turn off hasAggs if we find no aggs.
+ * It is possible for constant-expression simplification to remove
+ * all explicit references to aggs, but we still have to follow the
+ * aggregate semantics (eg, producing only one output row). */ if (parse->hasAggs)
numAggs = count_agg_clause((Node *) tlist) + count_agg_clause(parse->havingQual); /*
*Figure out whether we need a sorted result from query_planner.
